title: Roles of a solo LuxR in the biological control agent Lysobacter enzymogenes strain OH11.
abstract: Lysobacter enzymogenes is a ubiquitous plant-associated and environmentally friendly bacterium emerging as a novel biological control agent of plant disease. This bacterium produces diverse antifungal factors, such as lytic enzymes and a secondary metabolite (heat-stable antifungal factor [HSAF]) having antifungal activity with a novel structure and mode of action. The regulatory mechanisms for biosynthesis of antifungal factors is largely unknown in L. enzymogenes. The solo LuxR proteins have been shown to be widespread, playing important roles in plant-associated bacteria. Here, we cloned and studied a solo LuxR protein, LesR, from L. enzymogenes strain OH11. Overexpression but not deletion of lesR significantly impaired HSAF biosynthesis levels and antimicrobial activities but did not show visible effect on production of major lytic enzymes. Overexpression of lesR also led to remarkably accelerated cell aggregation and induced production of a melanin-like pigment in L. enzymogenes; these two phenotypes are mediated by the diffusible factor cell-to-cell signaling system of L. enzymogenes. The C-terminus helix-turn-helix domain was shown to be critical for several lesR-controlled functions. Overall, our study provides the first example of the roles and mechanisms of a solo LuxR protein in a plant-associated L. enzymogenes.
authors.forename: Guoliang
authors.initials: G
authors.lastname: Qian
authors.forename: Feifei
authors.initials: F
authors.lastname: Xu
authors.forename: Vittorio
authors.initials: V
authors.lastname: Venturi
authors.forename: Liangcheng
authors.initials: L
authors.lastname: Du
authors.forename: Fengquan
authors.initials: F
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000378:metabolism / Q000494:pharmacology*; D001487:Basidiomycota / Q000187:drug effects; D061046:Biological Control Agents; D015870:Gene Expression; D053528:Lysobacter / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D008543:Melanins / Q000378:metabolism; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000382:microbiology*; D010944:Plants / Q000382:microbiology*; D017434:Protein Structure, Tertiary; D011775:Pythium / Q000187:drug effects; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017384:Sequence Deletion; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism
chemical_list: D000935:Antifungal Agents; D061046:Biological Control Agents; D008543:Melanins; D012097:Repressor Proteins; D015534:Trans-Activators; C064778:LuxR autoinducer binding proteins